Monday, April 26, 2010

Macroscopic quantum mechanics

In Greg Egan's Teranesia [1] one story I can't currently locate (h/t Mel Anderson, comments), the protagonist is fighting the ultimate infection. It seems impossibly mutable. Turns out it has evolved to exploit quantum effects, and it's finding the perfect mutation by exploring all the many worlds of variation.

That wasn't the only science fiction story of the past decade to imagine that biological organisms, operating at atomic scales, might exploit quantum effects. Alas, science fiction memes don't last long these days. Protein exploitation of quantum effects has become a mainstream research topic. This Nov 2009 Sci Am news article is a good overview of the underlying physics; note especially the resolution to the old debate about how the quantum/classical transition happens ...

... In the modern view that has gained traction in the past decade, you don’t see quantum effects in everyday life not because you are big, per se, but because those effects are camouflaged by their own sheer complexity. They are there if you know how to look, and physicists have been realizing that they show up in the macroscopic world more than they thought...

... This work suggests that, contrary to conventional wisdom, entanglement can persist in large, warm systems—including living organisms. “This opens the door to the possibility that entanglement could play a role in, or be a resource for, biological systems,” says Mohan Sarovar of the University of California, Berkeley, who recently found that entanglement may aid photosynthesis ... In the magnetism-sensitive molecule that birds may use as compasses, Vedral, Elisabeth Rieper, also at Singapore, and their colleagues discovered that electrons manage to remain entangled 10 to 100 times longer than the standard formulas predict...